31/12/20131 D.S. Instructions Test Details: Formative: EO 005.06 will be a practice of a food borne illness investigation (theory); and Summarise: As part.

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D.S. InstructionsTest Details:• Formative: EO 005.06 will be a practice of a food borne illness

investigation (theory); and

• Summarise: As part of PC 005 Part A and Part B.

Remarks: • As part of PC 005 Part B, the students are required to collect

food samples (funds required for food samples).

• Food Specific Attack Rate Menu provided

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CONDUCT FOOD BORNE INVESTIGATION

EO 001.04

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Aim: As a PMed Tech, you will be responsible for preservation of manpower. When our fighting force becomes incapacitated with illness and disease, you will have to identify the cause

to prevent the spread.

CONDUCT FOOD BORNE INVESTIGATION

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References:A. CFP 213 Canadian Forces Health Services ManualAMD213001FP001_19750820_PT01 B. Procedures To Investigate Foodborne Illness, Fifth Edition,

1999C. http://www.statcan.gc.ca/edu/power-pouvoir/ch11/mean-

moyenne/5214871-eng.htmD. http://www.statcan.gc.ca/edu/power-pouvoir/ch11/median-

mediane/5214872-eng.htmE. http://www.statcan.gc.ca/edu/power-pouvoir/ch11/mode/

5214873-eng.htmF. http://www.easycalculation.com/statistics/geometric-

mean.php

Lesson Objectives

• Identify food borne illness

• Identify biochemical contamination/decontamination of food and water

• Collecting food and water samples

• Analyzing food and water samples

• Interpreting food and water analysis

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Students InstructionsTime:• 4 x 50 min periods for lecture• 3 x 50 min period for ECTotal EO time = 350 min.

Method of Instruction:• Lecture/demonstration/practice

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Safety Statement

Student Instructions

Introduction

Foodborne Illness:

• Intoxications caused by ingestion of contaminated foods

• Toxin-mediated infections

• Infections caused when microorganisms invade and multiply in intestinal mucosa

Purpose of Food Illness Investigation

The purposes of a foodborne illness investigation are to:

1. Identify illnesses associated with an incident and verify that the causative agent is foodborne;

2. Detect all cases, the causative agent, the implicated food(s), and the place(s) where food was mishandled or mistreated;

Purpose of Food Illness Investigation

The purposes of a foodborne illness investigation are to:

3. Determine source and mode of contamination, processes or practices by which proliferation, and/or survival of the etiologic agent occurred;

4. Stop the outbreak or prevent further exposures;

Purpose of Food Illness Investigation

The purposes of a foodborne illness investigation are to:

5. Gather information on the epidemiology of foodborne disease and the etiology of the causative agents that can be used for education, training, and program planning, which can make an impact on preventing foodborne illness.

Investigate Outbreaks

Investigating an outbreak involves:• Receiving notification of illnesses that

might be foodborne• Interviewing ill persons and persons at

risk who remained well• Making Epidemiologic associations

from initial information • Forming hypotheses

Act on Notification of Illness

Receive complaints or alerts:An alert or complaint relating to food may involve

foodborne illness, food spoilage, adulteration of a product, mislabeling, or an unsanitary establishment. Alerts also can be initiated by reports from physicians, by records of foodborne pathogens isolated by laboratories, by calls to poison control centers, and by reports of treatment given in either hospital or private emergency rooms, or by emergency squads.

Log Alert and Complaint Data

Turn to examples on page 6, 7.

Refer Complaint to Proper Agency

• Develop a working relationship with such authorities so they will reciprocate in situations that may be associated with illness. Often an investigation requires efforts of more than one agency. Cooperation and prompt exchange of information between agencies are vital.

Prepare for the Investigation

1. Delegate tasks

2. Collect forms & equipment

3. Alert appropriate personnel

4. Consult laboratory

5. Get appropriate specimen containers

Assemble Foodborne Investigation Kit

• Sterile sample containers• Sterile & wrapped sample collection

implements• Specimen collecting equipment• Supporting equipment• Sterilizing agents• Refrigerants• Clothing (PPE)

Steps to Verify Diagnosis

1. Case histories (collection of data).

• Tentatively identify source

• Laboratory studies

• Personnel interviews

2. Prepare summaries of case histories.

Steps to Verify Diagnosis

3. Obtain clinicial specimens.

• Feces

• Vomitus

• Blood

• Urine

• Other instructions

Foodborne Diseases

1. Bacillus cereus gastroenteritis and enteritis

2. Staphylococcal intoxication

3. Clostridium perfringens enteritis

4. Campylo-bacter Jejuni enterocolitis

5. Pathogenic escherichia coli diarrhea

6. Salmonellosis

7. Botulism

Illness Incubation

Period

S&S Foods Contributing Factors

Bacillus cereus gastro-enteritis

½ to 5 hrs Nausea, vomiting, occasionally diarrhea

Boiled or fried rice, cooked cornmeal dishes, porridge, pasta

Storing cooked foods at room temperature; storing cooked foods in large containers in refrigerator; preparing foods several hours before serving

Staphylococcal intoxication

1 to 8 hrs, typically 2 to 4 hrs

Nausea, vomiting, retching, abdominal pain, diarrhea, prostration

Ham, meat and poultry products; cream-filled pastries; whipped butter; cheese; dry milk; food mixtures; high protein leftover foods

Storing cooked foods at room temperature; storing cooked foods in large containers in refrigerator; touching cooked foods; preparing foods several hours before serving; holding foods at warm bacterial-incubation temperatures; fermentation of abnormally low-acid foods; handling foods by persons with pus-containing infections

Illness Incubation

Period

S&S Foods Contributing Factors

Clostridium perfingens enteritis

8 to 22 hrs, typically 10 hrs

Abdominal pain, diarrhea

Cooked meat, poultry, gravy, sauces, meat-containing soups, refried beans

Storing cooked foods at room temperature; storing cooked foods in large containers in refrigerators; holding foods at warm (bacterial-incubating) temperatures; preparing foods several hours before serving; inadequate reheating of leftovers

Campylobacteriosis(campylobacter jejuni)

2 to 7 days, usually 3 to 5 days

Abdominal cramps, diarrhea (blood and mucus frequently in stools), malaise, headache, myalgia, fever, anorexia, nausea, vomiting

Raw milk, poultry, beef liver, raw clams, water

Drinking raw milk; handling raw poultry; eating raw or rare meat or poultry; inadequate cooking or pasteurization; cross contamination from raw meat

Illness Incubation Period

S&S Foods Contributing Factors

Pathogenic Escherichia coli diarrhea

1 to 10 days, typically 2 to 5 days

Water diarrhea followed by bloody diarrhea; severe abdominal pain; blood in urine

Hamburgers, raw milk, roast beef, sausages, apple cider, yogurt, sprouts, lettuce, water

Ground beef made from meat from infected cattle; ingesting raw meat or milk; inadequate cooking; cross contamination; infected persons touching ready-to-eat foods; inadequately drying and fermenting meats

Salmonellosis 6-72 hrs, typically 18-38 hrs

Abdominal pain, diarrhea, chills, fever, nausea, vomiting, malaise

Poultry, eggs and meat and their products, raw milk and dairy products, other foods contaminated by salmonellae

Storing cooked foods at room temperature; storing cooked foods in large containers in refrigerators; holding foods (including melons) at warm (bacterial incubating) temperatures; inadequate cooking and reheating;

Illness Incubation Period

S&S Foods Contributing Factors

Salmonellosis (cont.)

Preparing foods several hours before serving; cross contamination; improper cleaning of equipment; obtaining foods from contaminated sources; occasionally infected persons touching ready-to-eat foods

Illness Incubation Period

S&S Foods Contributing Factors

Botulism 2 hrs to 8 days, typically 18 to 36 hrs

Gastrointestinal symptoms may precede neurological symptoms. Vertigo, double or blurred vision, dryness of mouth, difficult swallowing, speaking and breathing; descending muscular weakness, constipation, dilated or fixed pupils, respiratory paralysis; fatalities occur

Canned low-acid foods (usually home canned); smoked fish; cooked potatoes; onions; garlic in oil, frozen pot pies, meat loaf, stew left overnight in ovens without heat; fermented fish eggs, fish, marine mammals, muskrat tails, seal flippers, uneviscerated fish

Inadequate heat processing of canned foods and smoked fish; post-processing contamination; uncontrolled fermentations; improper curing of hams and fish; holding foods at room and warm temperatures

Collect Food Samples

Turn to examples on page 48, 50.

Facts to be Ascertained

a. Where was the food obtained?b. When was it prepared?c. Was it reheated?d. In what type of container or wrapping was

it received?e. How was the food stored both before and

after cooking? Before and after being served? And

f. How and by whom was the food prepared?

Food HandlersParticular attention should be paid to:a.Recent illness in themselves or their families;b.Presence of infective lesions on hands or

other exposed parts of their bodies;c. Stool specimens, if considered necessary;

and NOTE: At least three stool specimens are required to prove or deny existence of Salmonella or Shigella carriers; and

d. Sore throats and upper respiratory disease – sputum, throat, or nasal swabs – should be taken as appropriate.

Hygiene Inspection

a. General cleanliness;

b. Water and plumbing;

c. Dishwashing efficiency – both by hand and machine;

d. Utensils – with respect to presence of metal contaminants or evidence of pool cleaning;

e. Condition of preparation tables;

f. Storage facilities, including refrigeration conditions;

g. Presence of pesticides, cleaning materials, and other poisons in the vicinity of food; and

h. Evidence of rodent or insect infestation.

Develop a Case Definition

Use Table B (pages 100-122) & Table D Guidelines for Confirmation of Foodborne Disease Cases and Outbreaks (pages 125-131)

1. Confirmed Case

2. Presumptive Case

3. Suspected Case

Make Epidemiologic Associations

Make time, place, and/or person associations:

a. Purchase foods from the same place;

b. Eat at the same establishment;

c. Attend the same event; and

d. Reside in a place common to all;

Formulate Hypotheses

a. The mostly likely type of illness;

b. The most likely vehicle involved;

c. Where and the manner by which the vehicle might have become contaminated; and

d. Other calculations that can aid in the formation of these hypotheses.

Expand the Investigation

Explain the Investigation: test hypotheses by obtaining additional information to confirm or refute their validity.

Obtain Assistance: if an outbreak investigation requires resources beyond your agency’s capacity, request assistance from other health professionals

Expand the Investigation (cont.)

Find and Interview Additional Cases: continue to search for and interview ill persons who have had time, place, or person associations with the identified cases.

Investigate Mishandled Food

1. Meet Managers - Introduce yourself to the person in charge and state your purpose upon arrival.

Emphasize that the purpose of the investigation is to determine events or activities that contributed to an outbreak of foodborne disease so that preventive measures can be taken.

2. Collect Samples of Suspect Foods

3. Interview Food Workers - Interview separately all persons who were directly involved in producing, harvesting, processing, packaging, preparing, or storing the food under investigation and other persons who could have observed these operations.

Trace Source

4. Trace Source of Contamination• Natural toxin• Poisonous substance intentionally added• Poisonous or physical substance

accidentally or incidentally added• Addition of excessive quantities of

ingredients that under these situations are toxic

Trace Source

• Toxic container or pipelines• Raw product or ingredient contaminated by

pathogens from animal or environment• Ingestion of contaminated raw products• Obtaining foods from polluted sources• Cross contamination from raw ingredients of

animal origin• Bare-hand contact by food worker

Trace Source

• Handling by an intestinal carrier of enteric pathogens

• Inadequate cleaning of processing or preparation equipment or utensils

• Storage in contaminated environment

Conduct Hazard Analysis

• Farms

• Shellfish

• Slaughter houses

• Transport

• Foodservice establishments, retail stores, open-air markets, homes

Observe Operations

• Observe from start to finish operations involving the product under investigation.

• Determine the likelihood that incoming foods bring foodborne pathogens into the establishment under investigation.

Observe Operations

• Measure time/temperature exposures of foods

• Measure pH of foods (if applicable)

• Measure water activity of foods (if applicable)

Factor AllowingSurvival of Pathogen

• Insufficient time and/or temperature during cooking or heat processing

• Insufficient time and/or temperature during reheating

• Inadequate acidification• Insufficient thawing followed by insufficient

cooking

Factors Allowing proliferation of Etiologic Agents

• Allowing foods to remain at room or warm-outdoor temperature for several hours

• Slow cooking• Inadequate cold-holding temperature• Preparing foods a half day or more before

serving• Prolonged cold storage for several weeks• Prolonged time and/or insufficient

temperature during hot holding

Factors Allowing proliferation of Etiologic Agents

• Insufficient acidification

• Insufficient low water activity

• Inadequate thawing of frozen products

• Anaerobic packaging or modified atmosphere

• Inadequate fermentation

Analyze Data

• Classify the illness• Identify affected groups • Test the hypothesis as to whether the outbreak was

associated with a common source• Determine a vehicle• Measure disease association• Calculate confidence interval and statistical

significance• Determine the necessity for further field or

laboratory investigation

Statistics Canada

Arithmetic Mean

Median

Mode

Geometric Mean

Arithmetic Mean

The mean of a numeric variable is calculated by adding the values of all observations in a data set and then dividing that sum by the number of observations in the set. This provides the average value of all the data.

http://www.statcan.gc.ca/edu/power-pouvoir/ch11/mean-moyenne/5214871-eng.htm

Median

If observations of a variable are ordered by value, the median value corresponds to the middle observation in that ordered list. The median value corresponds to a cumulative percentage of 50% (i.e., 50% of the values are below the median and 50% of the values are above the median).

http://www.statcan.gc.ca/edu/power-pouvoir/ch11/median-mediane/5214872-eng.htm

Mode

In a set of data, the mode is the most frequently observed data value. There may be no mode if no value appears more than any other. There may also be two modes (bimodal), three modes (trimodal), or four or more modes (multimodal). In the case of grouped frequency distributions, the modal class is the class with the largest frequency.

http://www.statcan.gc.ca/edu/power-pouvoir/ch11/mode/5214873-eng.htm

Geometric Mean

Geometric Mean Formula :

Geometric Mean = ((X1)(X2)(X3)........(XN))1/N

This tool will help you dynamically to calculate the statistical problems. Find average value of the numbers. Calculating Geometric Mean is made easier.

http://www.easycalculation.com/statistics/

geometric-mean.php

Plot an Epidemic Curve

0

10

20

30

40

50

60

70

10/8/2009 10/9/2009 10/10/2009

AM

PM

Date of Onset of Initial Symptoms

Number of Cases

Predominant Signs & Symptoms

• A symptom is felt by a person, whereas a sign is seen by an observer.

Signs & Symptoms Number of Cases Percent

Diarrhea 260 88

Abdominal Pain 122 41

Fever 116 39

Nausea 105 35

Headache 68 23

Incubation Periods & Median

An incubation period is the interval between ingestion of a contaminated food (containing sufficient quantities of pathogens or concentrations of toxins to cause illness) and appearance of the first sign or symptom of the illness.

Food-Specific Attack Rates

Food/Beverag

e

Ill (a)

Well (b)

Total (a+b)

Attack Rate (%) (a/a+b x

100)

Turkey 97 36 133 73

Dressing 88 33 121 73

Peas 77 28 105 73

Rolls 50 16 66 76

Milk 12 6 18 67

Coffee 59 39 98 60

PumpkinPie

22 14 36 61

Test for Statistical Significance

Reading Assignment:

Procedures to Investigate Foodborne Illness, pages 56-62.

Interpret Results

Each of the following factors should be consistent with the suspected agent:

• Incubation period• Type of illness• Duration of illness• Population affected• Contributory factors leading to contamination

of the food, survival of the pathogen from the effects of the process, and proliferation or concentration of the etiologic agent.

Use Outbreak Data for Prevention

The primary purposes of a foodborne disease investigation are to identify the cause, establish control measures, and take actions to prevent future illness.

Table B (page 100-122)

Keys A-H (page 133-140)

Outbreak Prevention

• Alert public to hazardous conditions

• Consider newsletter

• Distribute copies to physicians, hospitals, the food industry, others interested in foodborne illness & prevention

Prepare and Submit

Review Figure 2-3 Disease Caused By Foodborne Parasites,

CFP 213 page 2-44

Questions